1. Field of the Invention
The present invention relates to imaging devices. More specifically, the present invention relates to a pixel defect detecting circuit and method for use in solid-state imaging devices, such as charge-coupled devices (CCDs), for detecting pixel defects.
2. Description of the Related Art
Solid-state imaging devices, such as CCDs, typically detect and correct for image display errors, such as white defects. A white defect occurs such that a video signal region having a high signal level due to a crystal defect of a semiconductor device causes a higher brightness than an image portion therearound to bring a white pixel condition.
In a typical method for detecting image defects, when an image is picked up with uniform illumination (black or white), a pixel having the opposite pickup characteristics is detected as a defective pixel, and the address of the detected defective pixel is stored in a memory, such as an electrically erasable programmable read-only memory (EEPROM). The data corresponding to the defective pixel is interpolated from normal-characteristic data of pixels around the defective pixel. More specifically, as known in the art, uniform illumination (black) is obtained by shielding an imaging device from light, and a defect is detected. A pixel corresponding to a white defect signal on the screen that is completely shielded from light is detected as a defective pixel.
Another method for detecting defects is a real-time defect detection and correction method without using a memory, such as an EEPROM, as disclosed in Japanese Unexamined Patent Application Publication No. 2004-64512. In this method, a defect is dynamically detected in one frame from information of pixels around a target pixel, and the detected defective pixel is corrected within the same frame. This method allows detection and correction for up to an infinite number of defective pixels without a memory, and also allows more rapid detection and correction than detection of defects across frames.